Physically, ice cream is the most complex of dairy products, being a three-phase system consisting of air, liquid and solids. The desirable structure of ice cream, expressed in terms of body and texture, is due to the physical effects of homogenization, whipping and freezing and to the type, source and pretreatment of the mix ingredients. Ice cream can be classified as a foam, or a physico, chemical system containing a gas (air) dispersed in a liquid. Ice cream is a complicated foam, the continuous phase representing a partly frozen emulsion, the ice crystals and the solidified fat globules being embedded in the unfrozen water phase. Typically, in conventional ice cream formulations, the higher the fat level, the more pleasing and appetizing the texture and flavor are considered to be. In accordance with the Standards of Identity of the Food and Drug Administration of the United States, ice cream must contain at least 10% of milk fat. The texture, flavor and mouthfeel characteristics of ice cream, containing at least 10% milk fat, are considered substantially superior to the texture and flavor of frozen desserts containing lower levels of fat, producing an overall consumer preference which is substantially higher than very low fat or non-fat frozen dessert products which seek to mimic the characteristics of ice cream.
There has been substantial technical effort directed to the development of low fat and non-fat frozen desserts in order to provide consumers with products having reduced calories and reduced fat content while preserving the organoleptic appeal of fat-containing frozen desert products. Such efforts include the use of various types of indigestible fat-like materials, such as sucrose polyesters and polyglycerol polyesters which pass through the digestive system without absorption and without contributing calories or the effects of saturated fats, such as butterfat.
Early efforts to provide non-fat frozen dairy desserts were directed to simple formulations wherein the fat normally present in ice cream was replaced with additional non-fat milk solids. U.S. Pat. No. 3,510,316 to Decker is representative of such efforts. The Decker patent is directed to a non-fat frozen dairy dessert which allegedly has comparable body, texture and flavor which are comparable to high butterfat-containing frozen diary dessert of the same total solids content as ice cream. The solids content normally provided by butterfat is replaced by a combination of increased non-fat milk solids and low dextrose equivalent (DE) corn syrup solids. Non-fat milk solids contents are present in the range of 10% to 19%, sugar is present in the range of 9% to 13%, corn syrup solids are present in the range of 9% to 13%, stabilizer is present in the range of 0.2% to 0.5% and an emulsifier is present in the range of 0.04% to 0.15%. The non-fat frozen dairy dessert proposed in the Decker patent is highly desirable in that the contents of the dairy dessert are substantially natural products normally found in ice cream and highly modified or complicated materials are not required in the product. However, the non-fat frozen dairy dessert proposed by the Decker patent has not met with commercial success due to short shelf life and stability.
Efforts to produce non-fat frozen dairy dessert have grown increasingly more complex and numerous efforts have been expended to provide a non-fat frozen dairy dessert containing milk solids which has comparable body-texture and flavor to ice cream containing 10% milk fat. Substantial work has been carried out over an extended period of time with bulking agents, such as powdered and microcrystalline cellulose, in fat-containing a reduced fat food product including frozen dessert formulations. For example, U.S. Pat. Nos. 3,067,037, 3,141,875, 3,157,518, 3,251,824, 3,388,119, 3,539,365, 3,573,058, 3,684,523, 3,947,604, 4,199,368, 4,231,802, 4,346,120, 4,400,406, 4,427,701 and 4,421,778 relate to use of various types of cellulose in frozen dessert products. However, as the fat content is reduced in frozen desserts containing substantial levels of microcrystalline cellulose, adverse organoleptic effects such as a mouth-coating or astringency sensation, and a lack of a well-rounded organoleptic sensation corresponding to that provided by conventional milk fat-containing ice cream products, tend to become more pronounced.
U.S. Pat. No. 4,855,156 to Singer, et al., is directed to frozen whipped dessert products wherein part or all of the milk fat in an ice cream mix formulation is replaced by a macro-colloid comprising substantially non-aggregated particles of denatured protein having in a dry state a mean diameter particle size distribution ranging from about 0.1 micron to about 2.0 microns, with less than about 2% of the total number of particles exceeding 3.0 microns in diameter and wherein the majority of particles are generally spheroidal as viewed at about 800 power magnification under a standard light microscope. The particles in a hydrated state forming the macro-colloid have a substantially smooth, emulsion-like organoleptic character. Proteinaceous macro-colloids are derived from undenatured, substantially soluble proteins obtained from animal, vegetable and microbial sources, such as dairy whey, egg white albumin, soy and bovine serum albumin protein sources.
U.S. Pat. No. 4,400,405 to Morley is directed to a whipped emulsified frozen food of low fat content which is extrudable in continuous form at temperatures in the range of 0.degree. F. to 10.degree. F. for serving by extrusion at home freezer temperatures. The frozen food product of the Morley patent consists essentially of a controlled emulsion of protein, water, sugars, stabilizers and emulsifiers. The protein accounts for 3% to 7%, the water accounts for 54% to 60%, the sugars account for 25% to 29% and the emulsifiers and stabilizers account for 1.1% to 2.7%, all by weight of the product. The Morley patent relies upon providing a saccharide system containing various sugars, a stabilizer system employing at least one stabilizer from each of at least three groups of stabilizers and an emulsifier system having particular emulsifiers to provide an extrudable product at refrigeration temperatures.
U.S. Pat. No. 4,308,294 to Rispoli, et al. is directed to an oil-free, oil-replacement composition having an oily mouthfeel texture and lubricity used in products such as frozen dairy desserts. The composition is formed by hydrating and whipping a protein and a cellulose gum to form a protein phase, hydrating an acid stable modified starch and an acid to form an acid phase, then heating to swell the starch while minimizing bursting, followed by cooling and mixing the protein phase and the acid phase.
U.S. Pat. No. 4,840,813 to Greenberg, et al. is directed to low and non-fat aerated frozen dairy deserts which are alleged to have the organoleptic characteristics of premium, high fat ice cream but which include 0.1% to 7% by weight of fat. The dessert compositions essentially contain 20% to 25% milk solids not fat, 1% to 7% whey protein concentrate, corn syrup solids, sucrose and water. The whey protein to casein weight ratio ranges from 1:0.5 to 4.0. The Greenberg, et al. patent utilizes high temperature pasteurization to denature at least about 50% of the whey protein of the skim milk utilized in the manufacture of the frozen dairy dessert product.
U.S. Pat. No. 4,510,166 to Lenchin is directed to the use of converted starches, such as dextrins, acid-converted starches, enzyme-converted starches and oxidized starches, to replace fat in food products, such as mayonnaise and ice cream.
U.S. Pat. No. 2,590,077 to Lolkema is directed to the use of a highly modified and unusual starting product in a frozen dessert product. The starch product of the Lolkema patent is made by mixing starch (1000 parts by weight) with technical monochloroacetic acid (150 parts by weight) according to Dutch Patent 55,779, which corresponds to U.S. Pat. No. 2,459,108 to Lolkema. A mixture of starch, monochloroacetic acid and water containing 1/2-2 parts by weight of water per part by weight of the polysaccharide is passed over a rotating drum heated to a temperature of about 100.degree.-180.degree. C. on which the mixture is dried in a period varying from a few seconds to a few minutes. The ethers and esters obtained according to the '108 Lolkema patent consist of small, thin flakes which are removed from the drum after drying, which flakes will readily dissolve in water to homogeneous solution. The Lolkema patent states that the etherified or esterified starch must be produced by the method described to provide the starch in flake form in order for the modified starch to be effective for the stated purpose.
The '077 Lolkema patent specifically states that pregelatinized starch obtained by converting starch in the normal manner is not suitable for use in preparing a vanilla ice in that it will be necessary to use a larger proportion of binding agent and the ice, moreover, will have a more or less granular structure.
Furthermore, it is not clear that the Lolkema patent is directed to the preparation of non-fat frozen desserts. It is indicted in the '077 Lolkema patent, that the process according to the invention may be used both for ice creams and for ices which do not contain cream or another fatty material. However, the only example of the preparation of an ice cream product which is an ice is one wherein milk is utilized. Milk would produce a fat-containing frozen dessert product, since milk contains 3% to 4% milkfat. The Lolkema patent teaches away from the use of unmodified starch and indicates that unmodified starch, when used as a stabilizer for ices, produces ices that are not satisfactory, since they will have a more or less granular structure.
While frozen dairy dessert products of the present invention and those of the prior art are characterized as being non-fat products, from a practical standpoint it is impossible to remove all butterfat from milk in ordinary commercial cream separation processes. Usually, a few hundredths percent of butterfat remains in the skim milk after separating cream from the milk in the most efficient separators. When the skim milk is further concentrated, such as by providing dried skim milk, the butterfat content is increased in proportion to the degree of concentration. Non-fat dry milk solids (dried skim milk) may contain up to about 1.5% fat. Accordingly, the term "non-fat frozen dessert product" as used herein means frozen dessert products which may contain up to about 0.5% butterfat.
Accordingly, it is an object of the present invention to provide non-fat frozen dessert products having organoleptic, stability and body features comparable to those of fat-containing frozen dessert products. It is also an object of the invention to provide essentially non-fat frozen dessert formulations which have a high degree of shelf and flavor stability. It is a further object of the present invention to provide non-fat frozen dairy dessert products from natural materials which have properties comparable to frozen dairy dessert products having more than 7% butterfat.
These and other objects will become more apparent from the following detailed description.